1. Field of the Invention
The invention relates to a heat-insulated wall having two covering layers, which are configured to be substantially vacuum-tight, and are disposed at a distance from one another. The two covering layers are connected to one another by a connecting profile (which runs along their contour and is configured with an essentially U-shaped cross-section). The two covering layers together with the connecting profile, enclose an intermediate space which can be evacuated and filled with an evacuable heat insulating material.
In the case of heat-insulated walls and housings which are based on vacuum insulation technology, and as are used, for example, in the case of domestic appliances such as refrigerators and freezers, metallic materials, for example stainless-steel sheeting, are used as the outer covering layers for the walls and housings, owing to the requirement for long-term diffusion sealing. For reasons of diffusion sealing, metallic connecting profiles are once again used to connect the two outer covering layers and are welded to the outer covering layers in a diffusion-proof manner. In this case, in addition to thin sheet-metal strips, connecting elements formed from thin sheeting and constructed with a cross section like a U-profile are also used as connecting profiles. The material thickness of the connecting elements is in all locations in the same order of magnitude as the material thickness of the outer covering layers, in order to make it possible to ensure the necessary process reliability in the manufacturing sequence of the heat-insulated wall. However, owing to their thermal conductivity, connecting elements having such a material thickness result in the thermal conductivity of the heat-insulated wall rising. Such a rise is relatively unproblematic if glass-fiber panels are used as the filling materials for the heat-insulated walls since, owing to their characteristics, such panels allow the insulating walls to have an extremely low thermal conductivity. However, at the same time, the use of glass-fiber panels results in the manufacturing costs for the heat-insulated walls being relatively high, owing to the costs of the glass-fiber panels. Furthermore, owing to their relatively high density, the use of glass-fiber panels results in the heat-insulated walls and housings filled with them being difficult to handle. Not only is the handling difficult during the production and completion to form a refrigerator but, in the end, also for the end user, owing to the weight resulting from them. However, other available supporting materials, such as open-cell polyurethane foam or polystyrene foam which do not have the disadvantageous characteristics of the glass-fiber panels are unsuitable for use as a filling material for heat-insulated walls owing to the low thermal conductivity which can be achieved with their use in conjunction with the connecting profiles that are now available, since the rise in the thermal conductivity caused by the use of such connecting profiles for the heat-insulated wall reaches an order of magnitude that is virtually impractical for use in refrigerators.